You can set iTunes to update
iPod with selected playlists automatically when
you connect iPod. iTunes erases songs from iPod
that aren't in the selected playlists.

To set iTunes to update iPod with selected playlists,
connect iPod to your computer and open iTunes.
Select iPod in the iTunes source list. Then click
the Options button and select "Automatically
update selected playlists only."

To transfer playlists manually, click the Options
button and select "Manually manage songs
and playlists." Now you can drag individual
playlists from iTunes to iPod to transfer them.

Transferring playlists is useful if you only
want to update iPod with a portion of your iTunes
music library. You can also set iTunes to update
iPod automatically with selected songs only.

This document contains information from Help
Center, the help system included with your computer.